The present invention relates to a furnace for firing wire-like products, and in particular copper wires enamelled with a cladding of insulating plastics resin.
As is known, furnaces currently utilised for the firing the cladding of copper wires are of the continuous tunnel type, and include at least one chamber of elongate form in which the wire is caused to advance longitudinally. In a first portion of this chamber the solvents which impregnate the cladding resin are evaporated; in a second portion of the chamber, maintained at a temperature greater than that of the first portion, polymerisation and cross linking of the resin is effected.
Since the solvent vapours are pollutants the furnace generally includes an auxiliary unit which draws in a mixture of air and the said vapours at the end of the first portion of the chamber and passes it to a heating unit in which this mixture reaches the combustion temperature of the said vapours before being delivered to the chimney.
There are likewise known furnaces in which the said mixture, or at least a part of it, is further mixed with air at ambient temperature and a part of the new mixture thus obtained is reintroduced into the main chamber of the furnace to control its temperature, and a part is delivered to the chimney.
In both cases the mixture of gases delivered to the chimney has a relatively high energy content, and it is evident that the thermal energy thus dispersed must be regained by means of suitable heating elements.